In recent years, a driver's driving load greatly increases by improved multi-functioning of vehicles and an increased traffic density. The development of an adaptive-cruise-control (ACC) system aimed to lessen the driver's load and to improve convenience is underway. To construct the ACC system, a radar that detects a vehicle, a pedestrian or the like as an obstacle, a vehicle front or the like is often mounted in a vehicle. As this type of on-board radar, a scanning apparatus using a milliwave or a light is often used.
There is known a scanning radar including a moving portion that reflects a laser beam or the like and that scans the reflected laser beam in a direction of detection using a motor. For instance, a laser beam is scanned using a DC motor and a polygon mirror (see Nonpatent Literature 1). There is also known a scanning-type actuator configured so that a moving portion serving as a scanner is connected to a fixed portion by a leaf spring, and so that this moving portion scans a laser beam using a moving coil or the like.
Nonpatent Literature 1: “Development of the scanning laser radar for ACC system”, OSUGI et al., Denso Technical Review Vol. 6, No. 1, 2001 pp. 43-48.